You are right, it could be. The problem is that its the kind of thing that would be almost impossible to disprove if it were false. So you can always raise doub

You are right, it could be. The problem is that its the kind of thing that would be almost impossible to disprove if it were false. So you can always raise doubts about a supposed disproof. But it'd be really easy to prove if it were true and noone has offered proof. And there've been plenty of people who've looked for such proof, afaict. My default assumption in such cases is that it is likely false.